LWIP2.0.2 & FreeRTOS & MQTT 客户端的 使用

1、参考链接 ：http://www.nongnu.org/lwip/2_0_x/group__mqtt.html

2、首先移植好lwip,然后添加 lwip-2.0.2\src\apps\mqtt 文件下 的 mqtt.c 文件，如果有头文件问题，清解决头文件问题！

3、根据参考链接，做一下修改

下面代码中的MQTT 服务器 是我自己搭建的，你也可以找一台Linux 主机搭建一个。。2017年4月24日09:10:19

/*
* MQTT client for lwIP

* Author: Erik Andersson

* Details of the MQTT protocol can be found at: http://docs.oasis-open.org/mqtt/mqtt/v3.1.1/os/mqtt-v3.1.1-os.html *
*/

#include "oneNet_MQTT.h"

#include "string.h"

ip_addr_t mqttServerIpAddr;

//1. Initial steps, reserve memory and make connection to server:

//1.1: Provide storage

//Static allocation: //下面这两句转移到 MAIN.c 中
//  mqtt_client_t static_client;

//  example_do_connect(&static_client);

//Dynamic allocation:
//  mqtt_client_t *client = mqtt_client_new();
//  if(client != NULL) {
//    example_do_connect(&client);
//  }

//1.2: Establish Connection with server

void example_do_connect(mqtt_client_t *client)
{
struct mqtt_connect_client_info_t ci;

err_t err;

/* Setup an empty client info structure */
memset(&ci, 0, sizeof(ci));

/* Minimal amount of information required is client identifier, so set it here */
ci.client_id = "lwip_test";

// MQTT服务器地址为：59.110.142.105端口号为：1883
IP4_ADDR(&mqttServerIpAddr, 59, 110, 142, 105);//配置 MQTT 服务器地址

/* Initiate client and connect to server, if this fails immediately an error code is returned
otherwise mqtt_connection_cb will be called with connection result after attempting
to establish a connection with the server.
For now MQTT version 3.1.1 is always used */

//MQTT 服务器进行连接 ,并注册 “连接结果处理”的回调函数，2017年4月12日09:00:12

err = mqtt_client_connect(client, &mqttServerIpAddr, 1883, mqtt_connection_cb, 0, &ci);

/* For now just print the result code if something goes wrong */
if(err != ERR_OK)
{
printf("mqtt_connect return %d\n", err);
}
}

//Connection to server can also be probed by calling mqtt_client_is_connected(client)

//-----------------------------------------------------------------
//2. Implementing the connection status callback
//执行连接状态 的 回调函数
static void mqtt_connection_cb(mqtt_client_t *client, void *arg, mqtt_connection_status_t status)
{
err_t err;
if(status == MQTT_CONNECT_ACCEPTED)
{
printf("mqtt_connection_cb: Successfully connected\n");

/* Setup callback for incoming publish requests */
//注册 消息推送 回调函数 以及消息数据到来的处理函数
mqtt_set_inpub_callback(client, mqtt_incoming_publish_cb, mqtt_incoming_data_cb, arg);

/* Subscribe to a topic named "subtopic" with QoS level 2, call mqtt_sub_request_cb with result */
err = mqtt_subscribe(client, "subtopic", 2, mqtt_sub_request_cb, arg);

if(err != ERR_OK)
{
printf("mqtt_subscribe return: %d\n", err);
}
}
else
{
printf("mqtt_connection_cb: Disconnected, reason: %d\n", status);

/* Its more nice to be connected, so try to reconnect */
example_do_connect(client);
}
}

void mqtt_sub_request_cb(void *arg, err_t result)
{
/* Just print the result code here for simplicity,
normal behaviour would be to take some action if subscribe fails like
notifying user, retry subscribe or disconnect from server */
printf("Subscribe result: %d\n", result);
}

//-----------------------------------------------------------------
//3. Implementing callbacks for incoming publish and data

/* The idea is to demultiplex topic and create some reference to be used in data callbacks
Example here uses a global variable, better would be to use a member in arg
If RAM and CPU budget allows it, the easiest implementation might be to just take a copy of
the topic string and use it in mqtt_incoming_data_cb
*/

//这两个函数 一个 处理 消息头 一个 处理 具体的 数据

static int inpub_id;
static void mqtt_incoming_publish_cb(void *arg, const char *topic, u32_t tot_len)
{

//消息来了之后，先进入这里用于判断 是什么主题 的，2017年4月20日09:25:51

printf("Incoming publish at topic \" %s \" with total length %u\r\n", topic, (unsigned int)tot_len);

/* Decode topic string into a user defined reference */
if(strcmp(topic, "subtopic") == 0)
{
inpub_id = 0;
}
else if(topic[0] == 'A')
{
/* All topics starting with 'A' might be handled at the same way */
inpub_id = 1;
}
else
{
/* For all other topics */
inpub_id = 2;
}
}

static void mqtt_incoming_data_cb(void *arg, const u8_t *data, u16_t len, u8_t flags)
{
//消息来了之后先判断主题 上面那个函数，然后在这里是根据不同的主题，进行不同的处理

uint8_t tempBuff[20]={0};

uint8_t i;

//数据复制到到缓冲区，并加  字符‘0’结尾，因为 发送工具只能发送 字符 不能发送字符串，2017年4月20日09:24:43
for(i=0;i<len;i++)
{
tempBuff[i]=data[i];
}
tempBuff[i]=0;

printf("Incoming publish payload with length %d, flags %u\n", len, (unsigned int)flags);

if(flags & MQTT_DATA_FLAG_LAST)
{
/* Last fragment of payload received (or whole part if payload fits receive buffer
See MQTT_VAR_HEADER_BUFFER_LEN)  */

/* Call function or do action depending on reference, in this case inpub_id */
if(inpub_id == 0)
{
/* Don't trust the publisher, check zero termination */
if(tempBuff[len] == 0)
{
printf("mqtt_incoming_data_cb: %s\n", (const char *)data);
}
}
else if(inpub_id == 1)
{
/* Call an 'A' function... */
}
else
{
printf("mqtt_incoming_data_cb: Ignoring payload...\n");
}
}
else
{
/* Handle fragmented payload, store in buffer, write to file or whatever */
}
}

//-----------------------------------------------------------------
//4. Using outgoing publish

//使用 向外推送消息
//MQTT传输的消息分为：主题（Topic）和负载（payload）两部分

void example_publish(mqtt_client_t *client, void *arg)
{
const char *pub_payload= "Hello,MQTT!\r\n";//推送的有效数据(负载)
err_t err;
/*
*    最多一次，这一级别会发生消息丢失或重复，消息发布依赖于底层TCP/IP网络。即：<=1
*    至多一次，这一级别会确保消息到达，但消息可能会重复。即：>=1
*    只有一次，确保消息只有一次到达。即：＝1。在一些要求比较严格的计费系统中，可以使用此级别
*/
u8_t qos = 2; /* 0 1 or 2, see MQTT specification */

//=0 的意思应该是不保留有效负载（有效数据）
u8_t retain = 0; /* No don't retain such crappy payload... */

err = mqtt_publish(client, "pub_topic", pub_payload, strlen(pub_payload), qos, retain, mqtt_pub_request_cb, arg);

if(err != ERR_OK)
{
printf("Publish err: %d.\r\n", err);
}
else
{
printf("Publish Success.\r\n");
}
}

/* Called when publish is complete either with sucess or failure */
//推送消息完成后 的 回调函数
void mqtt_pub_request_cb(void *arg, err_t result)
{
if(result != ERR_OK)
{
printf("Publish result: %d\n", result);
}
}

//-----------------------------------------------------------------
//5. Disconnecting

//Simply call mqtt_disconnect(client)

static_client.conn_state=0;

/* Initialize MQTT client */
example_do_connect(&static_client);

while(1)
{

example_publish(&static_client,(void *)mqtt_pub_request_cb);

/* vTaskDelayUntil是绝对延迟，vTaskDelay是相对延迟。*/
vTaskDelay(2000);
}

上面 的服务器 地址 今天 已经 到期了 ，阿里 的 太贵了 没钱 续费了 哎 2017年6月26日17:15:40